The 1st law of thermodynamics doesn't specify that matter can be created nor destroyed, but that the total amount of energy in a closed system cannot be created nor destroyed though it can be changed from one form to another.
The third one is correct, not sure abt another one
Hydrogen is usually –1. This is INCORRECT. The oxidation number for H is +1.
Oxygen is usually –2. This is CORRECT.
A pure group 1 element is +1. This is INCORRECT. It does not follow. This will depend on the other elements and the overall charge.
A monatomic ion is 0. This is INCORRECT. Diatomic ion is 0.
Percent error can be calculated by the difference of the theoretical value and the measured value divided by the theoretical value multiplied by 100 percent.
% error = 27.26 - 27.2 / 27.26 x100
% error = 0.22%
A value close to zero would mean that the measured value is more or less near the actual value.
